1. Field of the Invention
The present invention relates to an anode and a lithium-ion secondary battery.
2. Related Background Art
The high-output lithium-ion secondary batteries are recently being used for power tools and automobiles (e.g., cf. Japanese Patent Application Laid-open Nos. 2005-63955, 2004-127913, 2005-317493, 2000-251890, 2003-142075, and 2005-222933). The lithium-ion secondary batteries used for these purposes are required to provide high output and high safety together.
However, when the lithium-ion secondary battery is used for a power tool or an automobile, the anode is likely to undergo rapid entrance/exit of lithium ions. When the rapid entrance/exit of lithium ions occurs in the anode, lithium ions rapidly intercalate into an active material of the anode to cause extremely large expansion of the anode active material, whereby the anode is likely to undergo rapid deformation, which tends to pose a problem in battery performance and safety of the lithium-ion secondary battery. In the conventional technology, however, little study has been conducted theretofore on suppression of the rapid entrance/exit of lithium ions in the anode in the lithium-ion secondary battery.